1. Field of the Invention
This invention relates to fast-setting cementitious compositions. More particularly, it relates to a process for producing solid phosphorus pentoxide (P.sub.2 O.sub.5) containing materials suitable for use in fast-setting cements.
2. Related Art
Fast-setting cementitious compositions having utility for various purposes for which concretes are employed have been heretofore known.
U.S. Pat. No. 3,202,520 (Enoch, Aug. 8, 1965) discloses a rapid set non-hygroscopic cement composition consisting essentially of a blend of a phosphate derived from phosphoric acid and of alumina, and containing from 15 to 55 weight percent of P.sub.2 O.sub.5 and from 45 to 75 weight percent of alumina, and from 5 to 18 weight percent of magnesium oxide. The phosphoric acid is used in its liquid state then moisture is removed by drying the blend above 212.degree. F.
U.S. Pat. No. 3,525,632 (Enoch, Aug. 25, 1970) discloses a rapid setting concrete cement composition which comprises dry blending magnesium containing compounds, aluminum containing compounds and phosphorus containing compounds from stated sources in stated weight percentages, and then pulverizing the blended material without a separate drying stage. The phosphorus containing compound is a mixture derived from phosphoric acid, and at least 50 weight percent of one of trimagnesium phosphate, aluminum orthophosphate, and phosphoric anhydride.
U.S. Pat. No. 3,879,209 (Limes et al., Apr. 22, 1975) discloses a process for making a fast-setting concrete comprising establishing a mixture of an aggregate, containing at least 10 percent by weight of magnesia, and ammonium phosphates in aqueous solution. This patent further discloses that a commercial (agriculture fertilizer) product known as sequestered phosphatic solution (SPS) is particularly suitable as the source of the ammonium phosphate. The ammonium component is an essential feature of this invention.
U.S. Pat. No. 4,059,455 (Limes et al., Nov. 22, 1977) discloses a process for making a fast-setting concrete comprising establishing a mixture of an aggregate, containing at least 1% magnesia, and ammonium phosphates in aqueous solution. Again, the ammonium component is essential for attainment of the desired results of the invention.
U.S. Pat. No. 4,174,227 (Tomic, Nov. 13, 1979) discloses a grouting system comprising an acidic reactive component comprising at least one acidic oxy phosphorus compound selected from phosphoric acids, anhydrides of phosphoric acids and salts of phosphoric acids with multivalent metal cations, and a basic reactive component comprising at least one basic metal compound of a Group II or Group III metal capable of reacting with the oxy phosphorus compound(s) in the presence of water to form a monolithic solid. This patent teaches that the monovalent salts of phosphoric acid, e.g. the ammonium phosphates, do not develop early pull strength.
U.S. Pat. No. 3,821,006 (Schwartz, June 28, 1974) discloses a patching composition consisting essentially of a reactive component of MgO with an acid phosphate salt and an inert aggregate component. The particle size of the inert aggregate component is related to the compressive strength of the cement formed at an early cure age.
The mixtures employed in the methods of the patents discussed above set, and develop usable strength much more rapidly than conventional materials. Nonetheless, each of these patents is limited (as discussed above) and therefore distinguishable from the mixtures and processes of the present invention in several ways.
U.S. Pat. No. 3,673,111 (Hovarth, June 27, 1972) discloses a process for manufacturing a solid phosphoric acid catalyst in which a siliceous adsorbent is admixed with a polyphosphoric acid. The mixture is heated at an elevated temperature and thereafter extruded. The extrudate is further treated by drying first in a steam atmosphere and then in a dry air atmosphere. This patent does not teach a process for producing solid P.sub.2 O.sub.5 containing material suitable for use in fast-setting cements but rather teaches a process for making a catalyst.
U.S. Pat. No. 3,475,188 (Woodhouse et al., Oct. 28, 1969) discloses a dry refractory composition consisting essentially of phosphates absorbed on diatomaceous earth up to 80% by weight being absorbed thereon, magnesium oxide and refractory aggregate. Compositions and processes in which well above 80% by weight of phosphates absorbed on diatomaceous earth are present would be advantageous.
A fast-setting cementitious composition in which the phosphorus pentoxide reactive component is a solid and further can be derived from industrial wastes and can be premixed and preblended with a solid component such as magnesium oxide would be advantageous in that an economic, solid blend could be easily packaged, inventoried, handled and transported to the intended application site, then combined at the site with a readily available aqueous component such as water to form a solid. For example, a solid P.sub.2 O.sub.5 containing material could be premixed with a solid component, e.g. magnesium oxide, and optionally a solid aggregate to form a one component cement mixture, instead of the current two component P.sub.2 O.sub.5 containing solution and MgO containing solid that are separately packaged. It would be even more advantageous to utilize a solid waste that heretofore has created significant disposal problems.
It is an object of the present invention to provide a process for producing solid phosphorus pentoxide containing materials suitable for use in fast-setting cements.
Other objects and advantages of the present invention are shown through the specification.